from multiprocessing import Pool
import os, time, random


def long_time_task(name):
    print('Run task %s (%s)...' % (name, os.getpid()))
    start = time.time()
    time.sleep(random.random()*3)
    end = time.time()
    print('task %s runs %0.2f seconds' % (name, (end-start)))


if __name__ == '__main__':
    print('parent process %s' % os.getpid())
    p = Pool()
    for i in range(5):
        p.apply_async(long_time_task, args=(i,))
    print('Waiting for all subprocess done...')
    p.close()
    p.join()
    print('All process done')
